Generally, radar antennas are covered with a weatherproof enclosure, called a radom or bumper to protect the antenna. Even though the radom/bumper is constructed of material that minimally influences the radar waves, the angular accuracy of a radar sensor is affected and the antenna beam pattern is distored. Thus is a need for a measurement method and setup to measure the effects on the radar wave caused by the radom/bumper.
WO 2015/043935 A1 discloses a method for monitoring a cover of a Doppler radar sensor of a rail vehicle, using two adjacent antenna arrays, wherein a first radio signal is transmitted by a first antenna array, the said radio signal is at least partly reflected by the cover to be monitored and measured by a second antenna array. On the basis of the reflected signal, measured by the second antenna, dirt present on the cover is automatically detected. However, said document does not show a test antenna comprising several antenna elements in elevation and/or azimuth direction to evaluate the effect of radar waves caused by a radom or bumper. WO 2015/043935 A1 only detects dirt on a cover based on reflection measurements, wherein the transmitting antenna array and the receiving antenna array are located at the same side of the cover and since said document does not disclose the measurement of the influence on the radom/bumper material on radar waves with a test antenna. There is a need to provide a system and method with a test antenna, a radar sensor antenna, a radar sensor antenna cover.